The long term objective of this project is to examine the incidence and natural history of neuropsychological deficit, structural brain abnormality, and psychopathology in HIV seropositive men. In addition, a major goal of the project will be to identify factors which may be useful in the prediction of the occurrence or course of these abnormalities. It will be of considerable value for individuals infected with HIV as well as those who care for these individuals to have an appreciation of the risk of developing symptoms of AIDS Demetia Complex. Knowledge of predictors of the nature, or course of symptoms will have impact on societal agencies which must plan for the long term care and treatment of patients with HIV infection. The goals of the study will be to identify the characteristics of subjects who develop AIDS Dementia Complex, how immunological changes relate to changes in neuropsychological performance, and to develop an understanding of the factors that influence the development of emotional adjustment problems in patients with HIV infection. This study will be performed in conjunction with an existing AIDS Clinical Trials Unit which has an established cohort of approximately 200 subjects. Additional subjects will be recruited and followed at six month intervals. The examinations will include detailed neuropsychological examinations, Magnetic Resonance Imaging Scans, and structured psychiatric interviews and self ratings of distress. Changes in the variables will be examined in the context of changes in disease progression and immune status. It is hypothesized that declining immune status and progression to more advanced stages of HIV infection will be related to deteriorations in neuropsychological performance and increased incidence of abnormalities on MRI scans. It is also hypothesized that different patterns (rates) of disease progression may be identified, and that comparison of patient groups with different rates or progression will be useful in identifying the factors which predict rate of symptom progression.